Educational devices which demonstrate or illustrate the laws of physics are well known in the prior art. In general, only a few selected experiments can be performed with the aid of such prior devices; moreover, the type of experiments provided for by specific devices is usually oriented toward a single level of knowledge and understanding on the part of the students.
The present invention is adapted to overcome the limitations of the prior art by providing an inexpensive but reliable teaching apparatus for performing a variety of experiments relating to the kinetics of rigid bodies which are meaningful for grade school as well as for college students.
The apparatus, in kit form, includes an assortment of solid and hollow balls of different diameter and mass, and an inclined track defined by the parallel top edges of a pair of identical elongate, vertically aligned members which are spaced from one another. The track has the shape of a double incline which consists of two declivities of equal length, symmetrically sloping down from opposite ends toward a center where they are smoothly joined to each other. Detents are provided at opposite ends of the track to retain the balls placed thereon. Energization of electromagnetic relay means by actuation of a single, remote switch causes the detents to swing out of the way, thereby releasing the balls simultaneously for movement toward one another. A graduated scale is aligned with the track for measuring the distances traveled by each of the balls.
An easily comprehensible type of experiment would involve the movement of one ball released at one end of the track. The distances traversed by balls of different properties past the center, up the opposite slope and back again, can be measured, correlated and expressed in simple mathematical formulae. The speed of travel can be calculated as a function of distance per time, and so on. On the grade school level such experiments teach the basic skills of scale reading and record keeping; by combining observational procedures with a measurement approach, children learn how to find solutions to problems, and how to validate their answers. On a more advanced level the fundamentals of statistics and geometry may be introduced. The decelerating force of friction may be studied with respect to engineering problems, and the coefficient of friction may be evaluated for an uncoated track as well as for various surfactants. Conservation of energy and momentum, for instance, or acceleration due to gravity, suggest an analytical approach to elementary kinetic equations, vectors and mathematical calculus. Another group of experiments involving two or more balls of identical or different properties simultaneously released from opposite ends of the track and undergoing elastic or inelastic collisions, may be used to introduce the mathematical concepts of differential equations and their application to the phenomena of oscillations or the time constants associated with damping.
Another demonstration of physical principles may be performed by rolling two hollow balls down the opposite declivities. One of the balls may be filled with oil and the other with water, to illustrate how the respective velocities are affected by the liquid with which they are filled. Yet another group of experiments may be performed by placing a block on the planar surfaces of the top edges for movement with the platform of a hand-held spring scale, and by comparing the difference in force required to support the object on the tilted surfaces compared to the force required to support it vertically on the scale platform.
These experiments and others which readily suggest themselves to one skilled in the art indicate the versatility and flexibility of the invention, and its applicability to teach the methodology of scientific endeavor as well as specific subjects in the physical sciences. Beyond this, it stimulates inventiveness in proposing additional experiments which is an important part of the learning experience. Due to the compactness of the kit, its simple construction and the ease of operation, the apparatus may be used without an instruction manual and without supervision of the students on the part of the teacher.